A Young Woman With Difficulty Swallowing

A 20-year-old woman presented for evaluation of progressive dysphagia for approximately 2 years, worsening during the last 4 months. She had lost 70 lb. For these reasons, she had chest x-rays and various endoscopic procedures and was later referred for neurologic evaluation.

Past medical history was significant for a nonspecific arthritis at the age of 10 that lasted for 2 years.

Neurologic examination revealed normal mentation. Extraocular movements were normal, and she had only minimal ptosis on the left. She had a horizontal smile ( Fig. 72A-1 ) and bilateral facial weakness, her speech had a nasal quality, and her palate did not move. Her tongue was not atrophic but was weak. Other cranial nerves were normal. Neck flexors and extensors were 5−/5, and she had 4/5 weakness of the proximal muscles of the arms with mild fatigue. There was no muscle wasting or scapular winging. Reflexes were brisk but normal and symmetrical. Sensory examination and coordination were normal. No fasciculations were detected in the tongue or limbs. There were no Babinski signs. Gait and the rest of the examination were unremarkable.

What is the Differential Diagnosis?

This patient had weakness and difficulty swallowing; progressive spinal muscular atrophy is unlikely due to the recent onset of symptoms, the hyperreflexia, and the lack of fasciculations. Other motor neuron diseases are also unlikely, particularly because of her age. The differential diagnosis should include myasthenia gravis or a myopathy, such as polymyositis. Oculopharyngeal and facioscapulohumeral muscular dystrophy are unlikely because of the lack of family history, the recent onset of symptoms, and the lack of facial weakness, or the characteristic muscle atrophy in the latter. The lack of systemic manifestations and normal eye movements is against a mitochondrial myopathy.

What Tests Should Be Done?

Serum creatine kinase and thyroid-stimulating hormone tests were normal. An edrophonium test demonstrated mild improvement of speech and horizontal smile. Complete blood count and metabolic profile were normal, as were FANA and a CT scan of the chest. Acetylcholine receptor antibodies were not elevated. Her insurance company refused to pay for muscle-specific protein kinase antibody measurements.